WHAT IS SPRING WATER AND HOW IS IT SO SAFE?

The quality of water discharged by springs can vary greatly because of factors such as the quality of the water that recharges the aquifer and the type of rocks with which the ground water is in contact. The rate of flow and the length of the flow path through the aquifer affects the amount of time the water is in contact with the rock, and thus, the amount of minerals that the water can dissolve. The quality of the water also can be affected by the mixing of freshwater with pockets of ancient seawater in the aquifer or with modern seawater along an ocean coast.

So, should you feel confident about whipping out your canteen and filling it with cool and refreshing spring water? No, you should be cautious. The temperature of an Ozark spring comes from its passing through rock at a mean annual temperature of 56 degrees Fahrenheit. The water is crudely filtered in the rock, and the time spent underground allows debris and mud to fall out of suspension. If underground long enough, lack of sunlight causes most algae and water plants to die. However, microbes, viruses, and bacteria do not die just from being underground, nor are any agricultural or industrial pollutants removed.

By the way, a spring is defined as a concentrated discharge of ground water to the surface. Ground water flows through aquifers (literally, water-bearers) from recharge areas, on uplands, where it is replenished by rainfall and snow melt to discharge areas, in valleys, where it flows to the surface into streams and rivers, providing them with dry-weather flow (see diagram above from Driscoll, 1987). When the flow paths are focused by either topographic or geologic factors, ground water will flow to the surface.

Most springs in can be generally classified as gravity springs. The water flowing from the recharge area has energy derived from the higher elevation of that area. This gravitational energy forces the water to move through the sand or rock of the aquifer. Most of the time, the energy is pretty much used up by the time the ground water discharges to a stream. Most springs are less spectacular than this. They often form where the slope of the land is steeper than the slope of the ground water surface (the water table), so that the ground water reaches the surface and flows out.

A spring develops best when the flow of this discharging water erodes the surface soil, forming a gully or rill, thus creating a low spot where more water can discharge. Such springs often form the headwaters of small streams, and are common around the edges of sand plains in southern Maine. The spring may continue to grow as the gully deepens and lengthens back into the slope, capturing more water. Water can also find its way to the surface through natural bedrock fractures, or through a sand layer sandwiched between clay layers.

These more permeable collectors, again, serve to focus the flow of ground water so that it flows from a small area instead of seeping from the entire hillside. The original Poland Spring was described in 1909: "The water issues from cracks in a dike of porphyry which is about 10 feet wide at the spring and strikes about N 80 degrees W, as nearly as can be estimated" (Clapp and Bayley, 1909). There were many developed springs in the late 1800's and early 1900's.

A 1906 U.S. Geological Survey census showed 44 commercial springs in southern Maine alone. Public water supplies were often from rivers and lakes (108 of 149), but many (29) communities used springs as their source of supply. Only a few springs still supply water to municipal supplies. Commercial springs often bottled water for the local market. Bottles of spring water were hauled by wagon from the spring, where they had been filled, to town, and delivered to customers.